1. Field of the Invention
The invention relates to a matrix printer with a matrix print head, in particular with a matrix pin print head, which is supported on a back and forth movable slider guided on a rail guide, wherein the print elements can be operated at a frequency higher than 1000 Hz and wherein the print elements are movable via an inking ribbon against an imprint-receiving substrate resting on a print substrate support.
2. Brief Description of the Background of the Invention Including Prior Art
The matrix print head of such a matrix printer is supported on or, respectively, attached to a slider. The slider is guided on a guide axle support, running parallel to the print substrate support. The guide axle support exhibits a circular cross-section and guides and supports the slider on a sliding support bearing of simple construction. A further axle, running in parallel to the guide axle support, is disposed remote relative to the position of the print substrate support. The guide axle support and the axle are made of metal and are supported in the printer side walls. The length of the guide axle support and the axle determines the possible path for the slider.
The print elements contained in the print head generate vibrations during the printing process based on the pin shooting frequency and further frequencies, or based on the specific kind of a particular textual material or of a graphic print structure. These vibrations excite resonance frequencies in the guide axle support, in the side parts, and in the casing by propagating beyond the print head and by passing through the slider. These vibrations are radiated as air-transmitted sound and form a part of the noise emitted by the printer.
It has been determined by way of measurement that excited resonance frequencies of the guide axle support and of the slider induce and decrease vibrations in the print head in such a way that a real deterioration of the generated print image occurs. Thus, there is present not only one single sound path through the equipment body, starting from the print head elements via the print substrate support, but in addition there is a second (return) sound path through the equipment body running in reverse direction from the print substrate support and print head via the slider through the guide axle support and the axle in each case into the two printer side walls.
In particular, sound can travel from the guide axle support via the slider into the print head.
A sound-damping and simultaneously sound-absorbing print substrate support is taught in the German Printed Patent document DE-3,538,762. The sound damping and sound absorption comprises a metallic print bar, a layer decreasing and absorbing vibrations, and a metallic intermediate layer. On the other hand, the sound attenuation is formed by a frequency-neutralizing insulating layer. The insulating layer is formed in this case by an elastic plastic layer, comprised of a plastic material of the polymer group.
It is in fact possible with this combination of sound absorption, i.e. reduction of the sound excitation in the body of individual parts of the printer, and sound-attenuation, i.e. neutralizing of resonance frequencies of certain individual parts of a printer, to avoid the vibration wave propagation via the print substrate support to the frame parts of the printer. It is however not possible in this way to prevent corresponding vibration waves, which are transmitted in "reverse" direction via the print head as well as the slider and the guide axle support and the axle onto further device groups of the printer. These "reverse" vibration waves also contribute to the noise formation.